This invention is directed to nocturnal penile tumescence and rigidity monitoring systems and more particularly to a novel monitoring system incorporating a single penile sensor to sense penile tumescence and penile rigidity.
Studies of male impotence have shown that men with psychogenic impotence who have difficulty in attaining an erection while awake, generally have normal erections while sleeping. The studies also show that men with organic impotence, whether awake or asleep, are incapable of developing a normal erection. As a result of these studies, the monitoring of penile tumescence during nocturnal periods has become one of the bases for diagnosing sexual impotency.
If nocturnal penile tumescence monitoring indicates that impotency may be due to psychological factors, an appropriate therapy program can be developed. If such monitoring indicates organic impotency, therapy is usually ineffective, and a penile implant or other suitable prosthetic device may be necessary to assist in the development of an erectile condition. Thus, nocturnal penile tumescence monitoring is a reliable basis for determining whether therapy will be helpful or futile in correcting male impotency.
Some patients who undergo nocturnal penile tumescence evaluation are found to have significant penile expansion without the requisite rigidity that is needed to effect vaginal penetration. An assessment of penile rigidity as well as penile expansion is thus necessary for proper diagnosis of erectile impotence, and studies have shown that the most useful assessment of an erection is its rigidity characteristics.
The recognition that nocturnal penile conditions provide important data for diagnosing male erectile impotence has resulted in the development of various devices and techniques for monitoring penile tumescence and rigidity.
One known device for monitoring penile tumescence is disclosed in PCT Publication No. WO83/03748, wherein strain gauges are placed in two locations on the penis. The strain gauges include mercury tubing that is lengthened when the strain gauge is stretched, thereby increasing the electrical resistance. A readout of such electrical resistance is furnished to a recorder which records the data. This device measures penile tumescence only and provides no indication of rigidity.
Another known device for monitoring nocturnal penile tumescence and rigidity as disclosed in U.S. Pat. No. 4,515,166, employs a cable that forms a noose-like fitting around the penis. One end of the cable joins a sprocket assembly that drives a potentiometer. Changes in penile circumference are expected to affect the dimensions of the noose, causing the cable to move the sprocket assembly and drive the potentiometer to produce a corresponding electrical response. The disclosed cable and sprocket arrangement is relatively cumbersome to use and the mechanical play inherent in such device can lead to inaccurate data. Consequently there is a need to make frequent calibrations of the sprocket and drive assembly.
U.S. Pat. 4,515,166 also discloses a system for measuring penile rigidity that includes a torque motor on an elongated member that encircles the penis. The motor is activated at intervals to apply a force on the elongated member that is measured and correlated with rigidity. The use of cable displacement as a measure of compressibility or rigidity is a relatively cumbersome arrangement having mechanical play that is likely to result in inaccurate data.
It is thus desirable to provide a device for monitoring penile tumescence and rigidity which can be easily installed on a patient, is comfortable to use during nocturnal periods and provides accurate data relative to penile tumescence and rigidity.